Pulverizer.



G-.;R. MITCHELL; 'PULVBRIZEB- APPLIo-A'ron rxLn Nov. 8, 1910.q n

Patented Sept. 17,1912.

GEORGE R. MITCHELL, F SYRACUSE, NEW

iran srariis ra'rnn'r oriana.

YORK, ASSIGNOROF ONE-THIRD TO JOHN WILLIAM SMITH vAND ONE-THIRD TO ROBERT CROASDALE, BOTH OF SYRACU'SE,

NEW YORK.

".PULVERIZER.

Specification of Letters Patent.

Application filed November 8, 1910. Serial No. 591,325.

To all whom t may conce/m Be it known that I, GEORGE R. MITCHELL, of Syracuse, in thecounty of Onondaga, in the State of New York, have invented new and useful Improvements in Pulverizers, of which thel following, taken in connection withthe accompanying drawings, is a full, clear, and exact description.

This invention relates to certain improvements in pulverizlers referred to in my pending application $75,591,324, tiled November 8,

i' 1910, and is adapted more particularly for reducing coal to a powdered condition for fuel which after initial ignition in a suitable burner or combustion chamber contin ues 'its combustion b'y converting the coal into gas and burning the gas by its own heat.

The main object is to render the operation of pulverizing the coal continuousbut gradual `under comparatively slow rotary action v,through the medium of separate `concentric series of centrifugally operated hammers coacting with a corresponding series of concentric grids, the openings in which gradually diminish in size from the innermost to thevoutermost grids. I

Another object4 is to provide one of the rotary elements with fan blades for forcibly expelling the coal powder from the coal pulverizer and if necessary forcing it into the combustionchamberv of the furnace.

Other objects' and uses will be brought out in the following description:

In the drawings Figure 1 is a longitudinal vertical sectional view of a coal pulverizer embodying the various features of my invention. Figs. Q and 3 are transverse sectional views of the same `pulverizer taken onv lines 2 2 and 3 3 Fig. 1 but looking in opposite directions.v

Fig. 4 is a `transverse sectional view through the hopper and feed screw taken on lines 4 4 Fig. l, showing particularly the feed controlling gates.

This machine comprises a pair of coaxial disks 1 and Q which are mounted respectively 'upon separate coaxial shaft sections 3 and 3 and are provided respectively with a plurality of concentric circular grids 4, 5 and 6 and corresponding circular series of centrifugally operated hammers 7, 8 and 9 all of which parts are mounted tate the shaft section 3 and correspond ing disk Q together with the hammers 7, 8 and 9 in v'the opposite direction. The disk 1 is provided with a central inlet M communicating with arfeed hopper 15 intowhich the coal is placed by hand or otherwiseso as to feed by gravity through a connecting chute 16 and inlet M into the inner circular grid lt It is desirable, however, to provide a mechanical feeding device for the coal and for this purpose I have provided an upwardly tapering feed screwf 17 centrally in the apex of the hopper 15 and coacting with laterally adjustable valves 1S the screw 17 being driven from the main shaft 3 through the medium of intermeshing gears -19 and a shaft 20 for the purpose of establishing a positive feed and also pre venting the coal from becoming clogged in' the hopper or chute 'while the valves 18- serve also-to prevent excessive accumulation of theA coal at the base of the screw and also regulate the amount of fuel fed by the screw so that such feed will be more unifornrx' Each of the circular grids `4, 5 and A6 is made up of a series of axially-projecting parallel bars spaced a suitable distance apart and secured at one end to the .disk" l and having their opposite ends provided with bearing members 21 consisting preferably of rollers connected to adjacent ends of the corresponding bars and riding upon suitable circular tracks 22 on-the inner face The openings in the grids v 4, 5 and 6 gradually diminish in size, those of the disk 2 in the grid 6 being comparatively tine and tend to hold back the previouslycomminuted particles until reduced tothe desired powdered forni by thehammers 9 These hammers are arranged in sets of, in this instance, two each, those of eachset being `pivotally mounted at one end upon suphousi-ng The shaft sections 3 and 3v project rammed sept. 17,1912?.

. porting pins or studs 23` which in turn 50 't `pairing the fuel for quick ignition and more Y vstuds v #23 being arranged in concentric' l rio'r of the case the outer 'grid powder practically disk #-2- are a series offan blades 26-' .projecting radially beyond the' periphery of, -6-and serving to collect' the powdered coal from the-intethrough a suitable discharge opening' 2 7 in one side of the case -10.- 'and preferably. tangential to 'the path of movement of the blades r`'6L-, the outlet and expel i being adapted v'to be connected directly -toa j, "burner or combustion chamber with which the pulverizer may be used. Y

" As previously intimated 'this machine is adapted to feed its pulverized product directly into afurnace and it is found to be expedientrto introduce a sufficient amount of air into the pulverized coal to hold the ignition may be more instantaneous and the lcombustion more complete and foi this purpose I provide the coal Afeeding' chute leading to the inlet' of thefmachine with. one' or more air inlets -30- through which an eX- l tra amount of air may be introducedto during th/ pulverizing much as the grids are interposed between mix.with the coal as the'latter enters the first grid.. The air and coal are therefore thoroughly mixed agitated together and Aprocess and inas- Y the air and -coal inlets and v:the outlet for the pulverized coal, it is apparent that the entire mixture'must 'emerge from the lastv grid in a thoroughly agitatedand mixed palpable powder is heldV more or less in suspension vand fed in this condition by the fan' blades directly into the furnace, thus preperfect combustion.

In .operation the coal is placed by hand or otherwise in the hopper -17- and then gravitafes into the interior of the innermost grid -;4-,' the passage of the fuel being y aided somewhat by suction 'produced by the operation of the fan #Q6- Now by rotating .the disks -land' -2- in opposite directions it 'is evident that the coal intro-.

duced into'the innermost grid -4-' will be ground into a more or less comminuted state.

by thev action of the hanimers -7- with the inner's'urface of said grid, until the particles of coal are sufficiently small to Vpass resistance lreadily yield thereby avoiding any liability in suspension so that' the mesmo through this grid and 4thence into `the'ise-c-` ondgrid' -5- where'a similar action takes .place between the hammer '8- and grid The openings-in the latter grid are somewhat smaller than those in the .grid -4- and therefore the particles of coal which 'may pass through the grid -5 will be somewhat smaller than those which have been prevlously passed through the'grid -4- This further pulverized coal passes through'the grid --5-A and into -the grid -6- where it isfurther reduced to a sub'- stantially povdered condition and in such condition drawn by suction of the? fan' through the interstices into the interior of the casing Q -10- and is then forced by the fan QG-through the loutlet -'27#-.

By rotating the grids and hammers in opposite directions in the manner described,

it is evident that the speed' of travel of each' is comparatively low or substantiallyonehalf of what would be required if the' grids u were stationary and at the same timethis speed issuiiiciently high to cause lthe hammers -7 to assume a vsubstantially radial position by centrifugal force when free from but under-such resistance may of injury to either the hammers or grids.. What I claim is: i l 1 ln a pulverizing machine, a plurality of concentric grids,'.a revoluble disk, a plurality of vconcentric rows of pivoted 'harnmers in close proximity to the grids' and' mounted upon one face .of said disk, and

radially projecting fans upon the periphery of said disk positioned outside of thepath 'o f movement of the hammers.

2. In a pulverizingmachlne, a rotary 'circular grid and means for rotating it, a series of pivoted hammers having their free ends 'disposed in close proximity to the inner face of the grid and means for rotating the hammers in a grid, a track positioned adjacent said hammers, rollers carried-by said grid adapted y for bearing .upon a track, radially and outwardly-projecting fans positioned adjacent said hammers, and grid hammers andxfan blades and said case' provided withan inlet and an outlet.

3. A' coal pulverizer 'comprising an inclosing case 'having' an inlet and `an outlet, a rotary circular grid, a concentric series of hammers, a rotatable supportffor the hammers, afan upon' said support, said support and grid mounted within the inclosing case, and meansfor rotating said gridvand support. g

4;. In a c'oal pulverizing machine, a plurality of rotary concentric grids "and a support therefor, a rotary hammer support having a plurality of circular rows of hammers pivotally `mounted thereon and operated centrifugally mtogrinding, coaction with an inclosing case for the izo the inner faces of their respective. grids, In `Witness whereof I have hereunut'eA Set means for rotating said supports in opposite my hand on this 17th day f October 1910.

directions4 fan blades mounted on one of the Y 1 supports, 21nd an ineiosing case for the grids, GEORGE R' MITCHELL 5 hammers and fan blades), having an inlet ad- Witnesses:

jacent thev grids and an outlet -adjacent'to H. E. CHASE, Y

the fan'blades. E. F. SPEARING. 

